M16 - Eagle Nebula in Ha

[that_guy (Tony)]

So I got my EQ6 Pier Extension tube and the damned thing is turning even though the centre bolt is tightened to all heck. I think polar alignment slipped when SGP did an auto meridian flip. While I enjoy having the scope not hit the tripod leg when it reaches the meridian, I particularly don't enjoy having to redo drift alignment. Oh well, thats the ranting part of the thread done.

Some good old M16 in Ha from my backyard. There are also odd halos(?) around the stars which I think might be registering artifacts. If anyone has seen these before please let me know. They are more prominent in the full res image.

40x 300sec Ha with QHY9/ED127/EQ6Pro
Full Res Astrobin Link

I wish I had pixinsight again. Feels bad having your images turn worse because you get used to using one software and the trial runs out .

Thanks for viewing! C&C is always welcome!

[Slawomir (Suavi)]

Nice result Tony. I think it is a tough game at such high resolution as you have (under 0.6" pp) - it is way past diffraction limit of your aperture and I'm wondering whether it would be worthwhile to experiment with binning 2x2 which would boost the SNR with not much loss of resolution in this case, and some detail could possibly be recovered with drizzle integration.

Halos around brighter stars remind me what I used to have with my ED doublet and 3nm filters - some out of band signal leaks through even the best narrowband filters resulting in halos, albeit in my case these were more pronounced because of using a doublet. I suspect it is predominantly blue signal that is causing halos around brighter stars. This is why I do not think that narrowband works well with achromats, since we can get halos even with triplets.

I noticed that my 12nm Astronomiks were giving me more noticeable halos with my ED doublet as opposed to 3nm Astrodons. It might not be only the bandwidth, but also how well both block out of band signal. I made a quick compassion here: http://www.iceinspace.com.au/93-770-0-0-1-0.html

[that_guy (Tony)]

Ahh, I think I figured out what the halos were. Half way through the sequence the neighbours turned on their bright porch light about 30deg away from where I was imaging. I think that light might have leaked through my Ha filter. I've never done 2x2 binning imaging, I've read somewhere that the QHY9 isn't the best for binned imaging, though I may be wrong.

[Slawomir (Suavi)]

Originally Posted by that_guy

Ahh, I think I figured out what the halos were. Half way through the sequence the neighbours turned on their bright porch light about 30deg away from where I was imaging. I think that light might have leaked through my Ha filter. I've never done 2x2 binning imaging, I've read somewhere that the QHY9 isn't the best for binned imaging, though I may be wrong.

Now I see you already drizzled your data. So I would certainly stick to bin 1x1 as it gives you a nice 1.17" pp.

I attach a tarp (stretched between two poles) to the fence to block neighbour's lights...having said that, such stray light should not introduce halos around bright stars - such light would only lower the overall SNR and possibly introduce some gradients across the image.

[multiweb (Marc)]

Looks pretty neat. Good details in the pillars.

[Andy01 (Andy)]

Nice image, well framed!
Btw, I met a guy at a star party with an EQ6/half pillar combo.
He glued a layer of sandpaper to each of the surfaces where the pillar meets the tripod,
So the sandpaper locks itself into position with it’s opposite number.
Said it works well for him- might be worth a try?